Secure direct contact-based visual communication method based on camera-display pairs

Abstract

The present invention introduces a secure bidirectional visual data communication method between user devices via direct contact. Each device is equipped with a camera, a display and a distance sensing unit, all located on the same side of the device. Communication is initiated when two user devices are brought into physical contact, establishing communication channels between the display of one of the devices and the camera of the other. The distance-sensing unit measures the proximity of the devices. Once the devices are in direct contact, a calibration process begins to align the camera position of the first device with the display of the other. This process involves dividing the display into multiple segments, each with a unique color identifier that changes periodically. With each iteration, the calibration area narrows until it focuses on a small, concealed area that is imperceptible to the human eye or external devices, where secure data exchange (e.g. cryptographic key agreement) occurs.

Description

[0001] SECURE DIRECT CONTACT-BASED VISUAL COMMUNICATION METHOD BASED

[0002] ON CAMERA-DISPLAY PAIRS

[0003] FIELD OF THE INVENTION

[0004] In general, the present invention relates to visual communication based on camera-display pairs. Specifically, the present invention relates to direct contact-based visual data communication based on camera-display pairs using time-varying color information.

[0005] BACKGROUND OF THE INVENTION

[0006] U.S. Patent Application 20130091302 discloses a method for visual information exchange between mobile devices using a camera-based protocol, where each device has a display and a camera on the same side. The data is encoded as a sequence of images displayed on a screen. These images comprise a two-dimensional pattern code analogous to barcodes or QR codes, utilizing a binary representation with black-and-white elements. Additionally, the image sequence contains an “alignment element” responsible for the clarity of perspective information placed in space. The communication is bidirectional and facilitates data exchange in both directions.

[0007] In contrast to the prior art, the present invention discloses a direct contact-based data transmission between two user devices with camera-display pairs. As a result of physical contact, the camera captures the display of the other device within its focal range. The image perceived by the camera is blurry because the target object (another device) falls within the focal range. Therefore, information is not transmitted conventionally, e.g. by a black-and-white pattern. Due to the proximity of the camera-display pairs (in direct contact), the information conveyed by e.g. a QR code cannot be processed. Therefore, the transfer data is represented by time-varying color sequences and / or color patterns.

[0008] U.S. Pat. No. 9,143,936 and U.S. Pat. No. 9,717,002 disclose methods for secure digital communication and authentication between mobile devices. It includes direct line-of-sight visual digital communication for controlled security, direct-contact motion-based digital communication, and several authentication methods such as secure code exchange and verification using human-readable information alongside machine-readable codes. To clarify, direct line-of-sight visual digital communication uses machine-readable codes such as QR codes, within a clear line-of-sight area, without any physical contact. The publication document also introduces another communication method based on direct physical contact and motion, where data is transferred through patterns of vibrations.

[0009] In contrast to the prior art, in the present invention a closed secure communication channel is established visually. The two user devices are in direct (physical) contact, the distance between them is 0 (close to 0 mm). The present invention requires monitoring certain environmental characteristics to ensure integrity. At the end of the calibration process, a small, physically secure area is established where secure data exchange occurs. Detecting various environmental aspects is critical for facilitating a secure and private communication channel. This visual communication cannot be observed by the human eye or any external device. The closed operation of communication relies on a distance-sensing unit, such as a proximity sensor, although not exclusively. The devices must be positioned in an idle state and not be displaced during the communication. Stability can be secured by utilizing other sensors, including but not limited to gyroscopes and accelerometers.

[0010] In contrast to the prior art, in the present invention the data is exchanged visually using timevarying color sequences and / or color patterns. Machine-readable codes (e.g. barcodes, QR codes, etc.) cannot be processed because of the physical touching, as the other user device is in focal range of the camera. Communicating with data represented by graphical image sequences is not feasible, the direct contact results in blurred images. Therefore, the present invention utilizes predefined time-varying color sequences and / or color patterns. Due to the blurred image, it also involves color correction algorithms to convert the captured color information to the closest predefined color or pattern.

[0011] U.S. Pat. No. 17,805,466 discloses a method for data transmission between touch devices, involving the exchange of signals to determine overlapping areas for signal intensity-based selection, culminating in a final data transmission process.

[0012] WO Patent Application 2015153067 discloses a display device with an integrated optical touch system and control system, enabling secure fingerprint-authenticated peer-to-peer data transfers. U.S. Pat. No. 8,256,673, U.S. Patent Application 20120292392, U.S. Patent Application 20160301821, U.S. Patent Application 20160292476, disclose methods for information exchange using time-varying barcodes, including error-identifying or two-way communication feedback loop communication via barcode images.

[0013] In contrast to the prior art, the present invention employs dynamic color data instead of barcode imagery. Furthermore, it applies color calibration techniques to match captured colors to predefined colors or patterns, rather than interpreting binary data encoded in barcode visuals.

[0014] U.S. Pat. No. 8,231,054, and U.S. Patent Application 20120298752 disclose a method for exchanging information between electronic devices using a sequence of time-varying barcodes displayed on one device and acknowledged by another, enhancing communication through active displays. These references teach the use of bar codes that have varying sections of bar code image pattern resolution within a single bar code pattern.

[0015] In contrast to the prior art, the present invention is not intended for communication via barcode image sequences due to the direct contact between user devices, which results in the camera capturing blurred images. Consequently, binary black-and-white information transfer is unfeasible. To address this, the present invention introduces an innovative method utilizing a fixed set of colors and color patterns to facilitate an effective communication.

[0016] In contrast to the prior art, in the present invention the user device’s display is partitioned into distinct calibration segments. Each calibration segment is defined by a specific color or color pattern sequence that is periodically repeated. When a calibration segment is selected, it is subdivided into smaller sections. This subdivision is recursively applied, effectively minimizing the calibration area size while maintaining simplicity, resulting in a small diminutive, concealed area. The communication within this area cannot be observed by the human eye or any external device. In this secure environment, critical data exchanges - such as cryptographic key agreements - are conducted exclusively within this small area.

[0017] SUMMARY OF THE INVENTION

[0018] Embodiments of the present invention provide a secure, visual data communication method between user devices (e.g. mobile devices). In one embodiment, the present invention provides direct contact-based visual communication. The user devices touch each other physically. Each user device is equipped with a camera, a display, and a distance-sensing unit, all located on the same side of the device.

[0019] The first aspect of the present invention provides a method for visual data exchange between user devices, comprising: communicating with time-varying color information; displaying color information on one user device’s screen; capturing this color information using another user device’s camera; utilizing a fixed set of colors or color patterns for communication between devices; applying color correction algorithms to convert the captured color information to the closest predefined color or pattern.

[0020] The second aspect of the present invention provides a calibration method between two user devices, comprising: initiating proximity detection to identify a corresponding target device; aligning the screen of the initiator device with the camera of the target device, and vice versa, to establish a bidirectional visual communication channel; displaying calibration segments on the initiator device, each segment having a unique color sequence or pattern that changes over time; capturing a portion of these calibration segments with the target device’s camera; displaying the captured color sequence or pattern on a larger area of the display of the target device; allowing the camera of the initiator device to capture the displayed sequence and / or pattern; comparing the incoming color sequence or pattern with previously shown versions on the initiator device; selecting a matching segment as the new target and narrowing the calibration field to this segment; iteratively refining the calibration operation until a very small, concealed area is achieved.

[0021] The third aspect of the present invention provides a method for secure communication, comprising; initiating a calibration process that results in a small, concealed area. This area is guarded by the direct, physical contact of the user devices, after the calibration process, the end result of calibration is a small, concealed area that is protected physically due to the user devices are in direct contact touching each other physically. The communication within this area cannot be observed by the human eye or any external device. In this secure environment, critical data exchanges - such as cryptographic key agreements - are conducted exclusively within this small area.

[0022] In another aspect, the present invention introduces a method for visual communication between two user devices, comprising: the user devices maintaining direct contact, the display of the user device aligning with the camera of another user device, positioned within the focal length of the camera, the image appearing blurred, captured by the camera. Traditional machine- readable codes, like barcodes and QR codes, are not suitable; the invention utilizes color information (time-varying color sequences and / or color patterns) to facilitate communication.

[0023] BRIEF DESCRIPTION OF THE DRAWINGS

[0024] These and other features of the present invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings in which:

[0025] FIG. ! depicts an illustrative user device according to an embodiment of the present invention.

[0026] FIG. 2A shows an example of moving a display of a first user device proximate a display of a second user device.

[0027] FIG. 2B shows an example of the first user device and the second user device of FIG. 2A positioned for a direct contact-based data transfer.

[0028] FIG. .3 shows a schematic layout detailing a calibration method for user device displays, where the display is divided into calibration segments.

[0029] FIG. 4 shows an example of the color sequence of a calibration segment that repeats periodically, providing clear identification for the segment.

[0030] FIG. 5 shows a communication system between two user devices, utilizing calibration segments and distance-sensing units to establish precise calibration and secure data transfer.

[0031] FIG. 6 shows a user device display calibration method, where a dominant calibration segment is identified, reduced, and subdivided through iterative calibration until physical overlap is achieved.

[0032] FIG. 7A shows a cross-segmental diagram of two user devices in direct contact, with the display of one device touching the camera of the counterpart device for secure data transfer.

[0033] FIG. 7B shows a cross-segmental diagram of two user devices establishing bidirectional communication channels between their displays and cameras. FIG. 8A-J shows another example for user device display calibration method with color patterns.

[0034] FIG. 9 shows an example of a flow diagram that outlines blocks of an alternative camera-display visual data transfer method.

[0035] The drawings are not necessarily to scale. The drawings are merely schematic representations, not intended to portray specific parameters of the invention. The drawings are intended to depict only typical embodiments of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements.

[0036] DETAILED DESCRIPTION OF INVENTION

[0037] Illustrative embodiments will now be described more fully herein with reference to the accompanying drawings, in which exemplary embodiments are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of this disclosure to those skilled in the art. In the description, details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the presented embodiments.

[0038] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the specification and the appended claims, the singular forms “a”, “an” and “the” include plural references unless the context clearly indicates otherwise. Furthermore, the use of the terms a, an, etc. does not denote a limitation of quantity, but rather denotes the presence of at least one of the referenced items. The use of the terms “first”, “second”, and the like does not imply any particular order, but they are included to identify individual elements. Moreover, the use of the terms first, second, etc. does not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. It will be further understood that the terms “comprises” and / or “comprising”, or “includes” and / or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and / or groups thereof. The word “connected” may refer to “electrically connected”. “Connected” may also refer to operations or actions between two or more elements.

[0039] The detailed description provided below in connection with the appended drawings is intended as a description of the present examples and is not intended to represent the only forms in which the present example may be constructed or utilized. The description sets forth the functions of the example and the sequence of steps for constructing and operating the example. However, the same or equivalent functions and sequences may be accomplished by different examples.

[0040] The forthcoming description of the calibration method of the user device and the display and camera and establishing a communication channel between the user devices applies to every user device, display and camera presented throughout the description.

[0041] As shown in FIG. 1, a user device 1 is shown in the form of a general-purpose computing device (e.g. mobile phone). User device 1 is only one example of a suitable user device and is not intended to suggest any limitation as to the scope of use or functionality of the invention. Regardless, the user device 1 is capable of being implemented and / or performing any of the functionality set forth hereinabove.

[0042] The components of user device 1 comprise a processing unit 11, a display 13, a camera 14, a distance-sensing unit 15, a system memory 17, a network adapter 18 and a system bus 12 that couples various system components including system memory 17 to the processing unit 11. The system bus 12 may support additional sensory unit 16 and I / O interfaces 19. System bus 12 may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. By way of example, and not limitation, such architectures include Industry Standard Architecture (ISA) buses, Micro Channel Architecture (MCA) buses, Enhanced ISA (EISA) buses, Video Electronics Standards Association (VESA) local bus, and Peripheral Component Interconnect (PCI) bus.

[0043] User device 1 is adapted to run computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types.

[0044] User device 1 is typically equipped with a variety of machine-readable storage media. These media types encompass all formats compatible with user device 1, comprising both volatile and non-volatile memory, in addition to removable and non-removable media. User device 1 is equipped with system memory 17. System memory 17 encompasses volatile computer-readable media, specifically including a cache memory 171, and a random-access memory (RAM) 172. Additionally, the system memory 17 comprises a storage system 173, commonly known as a “hard drive”, is incorporated to provide non-volatile storage capabilities for user device 1. System memory 17 is expected to contain at least one software package comprising a collection of program modules, each configured to perform the functions of certain embodiments of the invention.

[0045] The embodiments of the invention may be implemented as a computer-readable signal medium, comprising computer-readable program code. The program code is stored on a non-volatile, machine-readable storage medium and is distributed through various transmission channels, including both wired and wireless methodologies. User device 1 facilitates the transmission of data signals, spanning electromagnetic, optical, or hybrid forms, whether within baseband or carrier waves. Unlike a computer-readable storage medium, user device 1 is capable of conveying a program for utilization by or in conjunction with an instruction execution system, apparatus, or device.

[0046] A computer program 174 is integrated into the user device 1 and includes a variety of program modules 175. Program modules 175 may be stored in system memory 17 and are accessible to processing unit 11 for execution. The computer program 174 is embedded within user device 1, comprising various program modules 175, including, but not limited to, user interface interactions, communication protocols, and advanced processing algorithms. These algorithms include, among others, image processing algorithms, autofocus mechanisms, and exposure adjustment functionalities.

[0047] User device 1 is equipped with display 13, which may utilize a variety of display technologies including, but not limited to, organic light-emitting diode (OLED) displays, liquid crystal displays (LCDs), or other advanced visual technologies. The display 13 is capable of rendering images, videos, and other graphical data with high fidelity. The display 13 is further engineered to support high refresh rates, enhancing the visual experience with seamless motion, clarity and reduced latency. The display 13 is connected to the processing unit 11 through either a dedicated graphics bus or as part of the integrated system bus 12, ensuring efficient data communication and enhanced graphical performance. The camera 14 comprises one or more image sensors capable of capturing still images and video footage. The camera 14 is also designed to operate at high frame rates, enabling the capture of ultra-smooth slow-motion video and facilitating real-time image analysis. Camera 14 is connected to the processing unit 11 via a high-speed interface on the system bus 12, allowing for swift data transfer and processing of visual information. The functionality of camera 14 is supported by a suite of program modules within the system memory 17, which may include image processing algorithms, autofocus mechanisms, and exposure adjustment capabilities.

[0048] The distance-sensing unit 15 may be realized as a proximity sensor or depth-sensing camera system. Distance-sensing unit 15 is designed to precisely measure the distance between the user device 1 and another device. It enables data transfer upon direct physical contact between devices, facilitating a secure and immediate exchange of information. Distance-sensing unit 15 is capable of utilizing a range of technologies including, but not limited to, structured light projection systems, time-of-flight (ToF) sensors, and other depth-sensing mechanisms.

[0049] The network adapter 18 serves as the communicative interface for user device 1, providing connectivity with various network architectures. Network adapter 18 may support a multitude of standards, including but not limited to, Ethernet, Wi-Fi and Bluetooth. The network adapter 18 is designed to facilitate both wired and wireless communication protocols, ensuring versatile and robust connectivity options for the user device.

[0050] User device 1 is equipped with various components that facilitate user interaction, such as input peripheral. Additionally, user device 1 may also feature connectivity modules such as network interfaces and external devices 10 that enable linkage to other computational systems. The interaction with these peripherals is managed through VO interfaces 19.

[0051] User device 1 may optionally be equipped with additional sensory unit 16, which incorporates an array of sensors, including but not limited to, a gyroscope and an accelerometer. These sensors are integral to the device’s ability to discern its operational state, including the detection of idle positioning and the assessment of movement velocity. The gyroscope facilitates the determination of orientation, while the accelerometer measures linear acceleration. In concert, these sensors enable the user device 1 to detect when it is stationary or moving at a low speed, which can be critical for certain functions that require a stable or inert state. FIG. 2 A shows an example of moving a display of a first user device la proximate to a display of a second user device lb. In this example, the first user device la is in the process of being positioned for a direct contact-based visual data transfer with the second user device lb. The first user device la includes a display 13a, a camera 14a, and a distance-sensing unit 15a. The second user device lb also includes a display 13b, a camera 14b and a distance-sensing unit 15b.

[0052] FIG. 2B shows an example of the first user device and the second user device of FIG. 2A positioned for direct contact-based visual data transfer. In the example shown in FIG. 2B, the first user device la is lying on top of the second device lb, with the display 13a of the first user device la aligned and in direct contact with the camera 14b of the second user device lb. The display 13b of the second user device lb is also aligned and in direct contact with the camera 14a of the first user device la.

[0053] FIG. 3 and FIG. 4 are a schematic representation, providing one of many potential solutions for a calibration method applicable to user device displays. A display 13 of a user device 1 is segmented into various calibration segments 32. Each calibration segment 33 is associated with a distinct color information 40. Color information 40 includes a unique color sequence 41 which is repeated in time periodically. Color sequence 41 is unique and clearly identifies the specific calibration segment 33. FIG. 4 shows a schematic repeating color sequence: a first color 42, a second color 43, a third color 44 and a fourth color 45, which recur in a periodic manner as shown by a first color 42’, a second color 43’, a third color 44’ and a fourth color 45’. The calibration segment 33 displays a single color from the color information 40 at a time. In the color sequence, during the next time period the subsequent color from the color information 40 is displayed. The colors illustrated in FIG. 4, selected from a fixed set of colors, are examples only and do not delimit the range of applicable colors.

[0054] FIG. 5 depicts the establishment of communication channels 54 and 55 between two user devices la and lb. For the sake of clarity, the user devices are depicted face up, however, during establishment of a communication channel 54, 55 said devices are physically touching each other and the camera of one device faces the display of another, as follows. The first communication channel 54, originates from a display 13a of the first user device la and terminates at a camera 14b of the second user device lb. Similarly, the second communication channel 55, starts from a display 13b of the second user device lb and ends at a camera 14a of the first user device la. As illustrated in FIG. 5, the camera 14a of the first user device la is positioned to intersect with only a small area of the display 13b of the second user device lb. This intersegment is strategically limited to enhance calibration precision. Camera 14a is specifically aligned to detect a single, dominant calibration segment 57 emitted by the display 13b. Calibration segment 57 serves as a reference point for calibration. Conversely, the camera 14b of the second user device lb intersects with a similarly small area of the display 13a of the first user device la. Camera 14b is configured to detect a single, dominant calibration segment 56 emitted by the display 13a. This reciprocal arrangement ensures that each device can calibrate with the other with high precision and minimal interference. User device la includes a distance-sensing unit 15a, and likewise, the second user device lb is equipped with a distancesensing unit 15b. The function of the distance-sensing units 15a, 15b is to identify the presence of the other user device and to determine the distance between the two devices. Alternatives to a distance-sensing unit include, but are not limited to, the proximity sensor of the user device. Alternatively, depth-sensing unit of the camera may be provided for the same purpose. If the determined distance by the user device is small or zero, the direct (physical) contact is established. If the distance-sensing units 15a, 15b cannot ensure direct contact, communication may be suspended. The task of distance-sensing units 15a, 15b is crucial, if the user devices moved apart from each other, the communication channel is not physically covered, the secure visual data transfer should be suspended.

[0055] Reference is hereby made to FIG. 6, which presents a schematic representation of a user device 1 featuring a display 13. As depicted in FIG. 6, the display 13 includes a designated receiving area 62 that corresponds to the camera of another user device. On the display 13, there are distinct calibration segments visible. The camera of the second user device is initially aligned to receive a single, dominant calibration segment 63. In the following calibration iteration, the user device 1 reduces the calibration area to the previously established calibration segment and subdivides this smaller region into new calibration segments. Despite these changes, the receiving area 62 persists unchanged, as the user devices maintain a fixed position. The camera from the alternate user device consistently identifies a single, dominant calibration segment 64. This iterative calibration continues until a calibration segment 65 diminishes to a size that is physically overlapped by the user devices.

[0056] FIG. 7 A is a segmental diagram, that illustrates the direct contact-based touching of two user devices. A display 13a of a first user device la is in direct contact with a camera 14b of a second user device lb. A display 13b of the second user device lb is in direct contact with a camera 14a of the first user device la.

[0057] FIG. 7B is a segmental diagram, that illustrates communication channels 54, and 55 established between two user devices la, and lb. The first communication channel 54 is established from the display 13a of the first user device la to the camera 14b of the second user device lb. Conversely, the second communication channel 55 is established from the display 13b of the second user device lb to the camera 14a of the first user device la. This bidirectional configuration facilitates a seamless exchange of visual information between the user devices.

[0058] FIG. 8A-J shows another example for user device display calibration method with color patterns. FIG. 8 A illustrates a display 13 of a user device 1, populated with reference points. These reference points serve as vertices for triangles that span across the display. A single reference point 82 can concurrently belong to multiple triangles, meaning it is possible to construct multiple triangles around a single reference point. In the depicted calibration segment within FIG. 8A-J, a particular triangle 86 is formed by interconnecting three distinct reference points: a first reference point 83a, a second reference point 84a, and a third reference point 85a. The color associated with the first reference point 83a is designated as a first color reference 83b. Similarly, the second reference point 84a is associated with a second color reference 84b, and the third reference point 85a with a third color reference 85b. This sequence of color references - first 83b, second 84b, and third 85b - is established as a recurring pattern and uniquely identifies this calibration segment. As may be seen from FIG. 8B-J at any given moment, only one of the color references is active. Starting from each active reference point, a sector of a circle filled with that color begins to expand over a predetermined delta time interval. This expansion continues until the sector’s outer arc intersects with the corresponding edge of the triangle. The camera of the other user device is configured to capture color pattern information, which consists of three dominant colors that repeat periodically over time. The position of the camera within the calibration segment can be further refined based on the duration of the observed colors from this color pattern information. If the camera of another user’s device is close to one of the reference points, it captures the color reference for a longer period from that reference point. Consequently, the calibration area can be reduced more rapidly and made smaller. In this case, the second user device sends back the captured color information to the first user device by emitting the colors and duration of the colors. For example, if the duration of the third color reference 85b is double that of the second color reference 84b, the third color will be displayed for twice as long as the second color on the display of the second user device. This proportional representation of color duration facilitates a faster calibration. As a result, the calibration area can be reduced more quickly and to a smaller calibration area.

[0059] FIG. 9 shows a flow diagram of an example method for visual communication using cameradisplay pairs of the user devices. The process initiates with the initiator user device performing a proximity detection of a corresponding target user device in Pl. Through a particular alignment, the screen of the initiator device directly contacts the camera of the target device, while the display of the target device directly contacts the camera of the initiator device P2. This arrangement forms a bidirectional visual communication channel between the cameradisplay pairs. The initiator device displays calibration segments P3: the display is divided into small areas, and each of the areas has a unique color sequence and / or color pattern varying by time. The camera of the target device is in direct (physical) contact with the display of the initiator device. Due to the unique arrangement, the camera of the target device occupies only a small portion of the display of the initiator device. Only a portion of the calibration segments is captured by the camera of target device P4. Subsequently, the dominant color sequence and / or color pattern captured by the camera is displayed on a large area of the display of the target device in the following stage P5, allowing the camera of the initiator device to capture it in P6. The initiator device, in P7, compares the incoming color sequence and / or color pattern with the self-produced display versions shown previously. If a matching segment is detected, the initiator device selects this segment as the new calibration target and reduces the calibration field to this segment P8. The calibration operation can be iteratively refined until a very small, concealed area is formed P9. This small area is protected and covered physically by the user devices. The confidential data transfer occurs within a compact, physically shielded area formed as the end result of the calibration procedure PIO. This delimited region guarantees that the visual communication space remains exceedingly diminutive, thereby preventing discernment by the unassisted human eye or external surveillance, thus fortifying the confidentiality of the exchanged data.

Claims

AMENDED CLAIMS received by the International Bureau on 13 September 2025 (13.09.2025)Claims1. A method for visual communication between user devices using camera-display pairs for bidirectional data exchange, and wherein the devices are positioned in direct physical contact, characterized in that the method comprises: placing the transmitting display within the focal length of the receiving camera so that the displayed content appears blurred, thereby preventing recognition and decoding of machine-readable codes; performing an iterative spatial calibration process, comprising displaying predefined time-varying color sequences or color patterns on the display of the first user device and capturing them using the camera of the second user device, and progressively refining the alignment based on the captured data to identify a compact, optically aligned and physically shielded area; initiating a secure bidirectional visual data exchange by displaying further predefined time-varying color sequences or color patterns within the identified area; maintaining the direct physical contact between the user devices such that the overlap region forms a physically shielded optical channel, thereby physically shielding the aligned communication area and preventing interception by external observers.

2. The method of claim 1, wherein the calibration process comprises: segmenting the display of the first user device into a plurality of calibration segments, each associated with a unique time-varying color sequence or color pattern; capturing optical data from one or more of the calibration segments using the camera of the second user device; comparing the captured optical data with the predefined time-varying color sequences or color patterns to identify one or more matching calibration segments; iteratively refining the matching calibration segments through recursive subdivision to identify a compact, optically aligned area that remains physically obscured from external view due to the direct contact between the devices.

3. A method for visual communication between user devices using camera-display pairs for bidirectional data exchange, and wherein the devices are positioned in direct physical contact, characterized in that the method comprises: placing the transmitting display within the focal length of the receiving camera so that the displayed content appears blurred, thereby preventing recognition and decoding of machine-readable codes; performing secure bidirectional visual data exchange by means of predefined time-varying color sequences or color patterns within the identified blurred area; maintaining the direct physical contact such that the overlap region forms a physically shielded optical channel, protecting the visual data from interception by external observers.

4. The method according to any one of claims 1-3, wherein a distance-sensing unit located near the camera on the same user device is configured to activate or permit the secure visual communication process only upon detecting physical contact between the user devices, the unit comprising a sensing module, including but not limited to proximity, optical, or depth-based sensors.

5. The method according to any one of claims 1-3, wherein environmental lighting conditions are monitored during the visual communication process to verify physical shielding between the user devices and to detect potential gaps in direct contact.

6. The method according to any one of claims 1-2, wherein initiation and continuation of calibration process and secure data exchange are disabled or suspended in the absence of physical contact between the user devices.

7. The method of any of claims 1-3, wherein error correction coding is applied to timevarying color sequences or color patterns to compensate for optical noise and blur- induced distortion within the contact zone.

8. The method according to any one of claims 1-2, wherein the calibration process comprises rendering time-varying video, image sequences, or shader-generated patterns on the display, and performing color analysis on blurred visual content to enable optical calibration and identify a secure contact area without extracting encoded information.

9. The method according to any one of claims 1-2, wherein calibration is initiated within a predetermined sub-area of the display to reduce calibration time.

10. The method of claim 2, wherein the size or granularity of the calibration segments enables identification of an optically aligned, physically shielded area in a single iteration.

11. The method according to any one of claims 1-3, wherein the time-varying color sequences or color patterns comprise geometric patterns including circles, rings, or polygons, displayed in a predefined spatial and temporal arrangement.

12. The method according to any one of claims 1-2, wherein both devices perform the calibration process synchronously, triggered by a synchronization signal comprising a specific color, sequence, or pattern.

13. The method according to any one of claims 1-2, wherein the second device may transmit sensed color information via additional communication channels including, but not limited to, radio frequency communication, to speed up the calibration.

14. The method of any of claims 1-3, wherein cryptographic data is optically encoded using time-varying color sequences or color patterns readable only within a blur-defined focal zone created by direct device contact.

15. The method according to any one of claims 1-2, wherein environmental light conditions are measured, and the calibration patterns are adaptively adjusted in brightness and contrast to compensate for ambient lighting.

16. The method according to any one of claims 1-3, wherein replication, projection, capture, storage, or reproduction of the display output of the user device - whether internal or external - is prevented to preserve confidentiality of the visual data exchange.

17. The method according to any one of claims 1-2, wherein the iterative calibration is re- executed to compensate for misalignment caused by environmental changes or device movement.

18. A computer program comprising instructions which, when executed by one or more user devices, each having a display and a camera on the same side, cause the user devices to perform respective steps of the method of any one of claims 1 to 17, including visual calibration and secure visual data exchange.

19. A computer-readable medium comprising the computer program of claim 18.[0001]I. Article 19 Amendment to the Claims[0002]Pursuant to Article 19 PCT, the Applicant hereby submits a full replacement set of claims to supersede the claims originally filed with the international application.[0003]The amendments are submitted in response to the International Search Report (ISR) to address objections raised regarding novelty and inventive step, particularly in view of DI.[0004]II. Basis and Justification for the Amendments[0005]Iterative Calibration with Recursive Refinement (Claims 1-2, 8-10, 12-13, 17)[0006]The claims define an iterative calibration process in which the display is segmented, dynamic time-varying color sequences are displayed, and optical feedback is analyzed to progressively refine alignment. This recursive subdivision ensures convergence on a compact, optically aligned area. DI describes only general alignment and does not disclose iterative, segmentbased calibration, providing a technical improvement in precision and secure alignment.[0007]Physically Shielded Secure Contact Area (Claims 1-3, 10, 14, 16-17)[0008]The overlap region of the camera-display pairs forms a physically shielded optical channel, preventing external observation. While DI refers to general device contact, it does not disclose a deliberately shielded, optically aligned area. This ensures secure and protected visual communication, a technical effect absent in DI.[0009]Blur-Zone Security Obfuscation (Claims 1, 3, 8, 14)[0010]The transmitting display is positioned within the focal length of the receiving camera so that the displayed content appears blurred and machine-readable codes become unreadable. DI discloses near-contact alignment but fails to describe or suggest intentional use of blur as a security mechanism, providing a non-obvious technical advantage.[0011]Sensor-Gated Activation (Claims 1-6, 16)[0012]Communication is permitted only when physical contact is verified, with immediate deactivation if contact is lost. DI lacks a mechanism linking contact integrity to activation, making this feature novel and inventive, ensuring that the optical channel remains physically secured. Adaptive and Environmentally Responsive Calibration (Claims 5-7, 15, 17)[0013]Calibration is dynamically adjusted based on ambient lighting and device movement. DI provides no disclosure or suggestion of dynamic adaptation. This improves reliability and security, representing a non-obvious technical enhancement.[0014]III. Novelty and Inventive Step (Article 33)[0015]The amended claims meet the requirements of Article 33(1), (2), and (3) PCT, as they define subject matter that is both:[0016]• Novel: Iterative, segment-based calibration (Claim 2), physically shielded optical channel, blur-zone security, sensor-gated activation, and adaptive calibration are absent from DI, D2, and D3.[0017]• Inventive: None of the cited prior art suggests the recursive refinement of alignment to form a compact secure area, combined with blur-based obfuscation and sensor-gated activation. The invention improves security, precision, and robustness in visual communication, which would not have been obvious to a person skilled in the art.[0018]IV. Submission[0019]Accordingly, the Applicant respectfully requests that the amended claims attached hereto replace the original claims under Article 19 PCT. No changes are made to the description or drawings at this time.

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